Diaphragm for sound reproduction



June 2, 1931. K. LOCKE ET AL DIAPHRAGM FOR SOUND REPRODUCTION Filed Aug. 28. 1928 F/GI 3.

Patented June 2, 1931 UNITED STATES PATENT OFFICE DIAPHRAGM FOB SOUND REPRODUCTION Application filed August 28, 1928, Serial No.

This invention relates to a sound-reproducing diaphragm for loud speakers, talking machines or the like, in which curved strip-like or plate-shaped oscillating bodies {E are employed.

Sound-reproducing diaphragms of this type are already known, the oscillations being transmitted, tangentially to the surface, to the marginal rim of one or more 1 arcuate diaphragms. Such diaphragms, however, are attended with the drawback that the actuated marginal rim describes the most powerful oscillations, whilst the oscillations become progressively weaker towards the point of support of the diaphragm.

The present invention provides an improvement in this type of diaphragm insofar as, according to the invention, the diaphragm is set in more ample oscillation by imparting the oscillations to the diaphragm or oscillating bodies in the direction of the chord of the are or arcs, thus causing an amplified oscillation. For example, with this arrangement the centre of the surface oscillates more powerfully than the point of inception.

Moreover, a plurality of such oscillating bodies may be disposed side by side or one within another. The arrangement may also be such that the oscillatory oppositely acting surfaces encounter an interposed column of air interposed between them, which is suitably loosely coupled to the atmosphere, an arrangement which ensures very good reproduction of low frequencies. The arrangement also enables very large surfaces-for example of several thousand square centimetres-to be set in oscillation with a small amount of energy, thereby ensuring reproduction over a very wide range of frequencles.

In order more clearly to understand the invention, reference is made to the accompanying drawings, which illustrate diagrammatically and by way of example several typical embodiments of diaphragms constructed in accordance therewith Fig. 1 shows a simple bent oscillating body which is suitably fixed to a support at one side, and is actuated in the direction of the 302,466, and in Austria. February 2, 1928.

arrow, that is to say, in the direction of the chord.

Fig. 2 represents a bent surface, which may, of course also consist of two individual surfaces; and the surface or surfaces may be constructed of a plurality of strips or the like. In this case also, the oscillations are transmitted to the diaphragm in the direction of the chord of the arc.

Moreover, a plurality of such oscillating bodies may be combined to form a reproducing diaphragm, as shown in Fig. 3. In this case, the individual. oscillating bodies may also be made of different dimensions, in order to enable them to deal with different ranges of tones.

Fig. 4 is a diagrammatic representation of a diaphragm according to the invention, applied to a talking machine and actuated by a sound record disc and needle. The oscillating body 0 is actuated by the needle holder a. In this case the sound record is directed parallel to the surface of the sound record disc.

Fig. 5 shows a side elevation of a typical arrangement applied to a talking machine, in which the sound record is directed at right angles to the surface of the record disc; and Fig. 6 is a front elevation of this arrangement. The oscillating body or diaphragm c is preferably fixed into the top of a frame, and carries the needle holder at on its lower end, said holder running on the record 6 and moving up and down.

Fig. 7 is a side elevation, and Fig. 8 a front elevation of a typical loud speaker, the diaphragms in this case being connected by one straight border to the armature of the electro-magnetic operating means f, and secured at the lower opposite straight border to the frame 9 of the box, which latter may be covered in known manner with two coverings of stretched fabric or otherwise, permittlng passage of sound. The diaphragms have their convex surfaces mutually oppositely and outwardly directed and are integrally united at their free border which is acted upon by the electro-magnetic means f.

We claim 1. In a sound reproducing device, an open sided rectangular box frame, a straight-bordered curved diaphragm Within said box frame and secured by one straight border to one side thereof, and means mounted on said box frame for vibrating the opposite straight border'of said diaphragm in the direction of the chord of the curvature of said diaphragm.

2. In a sound reproducing device, an open sided rectangular box frame, a pair of straight-bordered curved diaphragms Within said box frame arranged with their convex surfaces mutually oppositely and outwardly directed and each secured by one stralght border to one side of said box frame, and

means mounted on said box frame for vibrating the opposite straight border of each of said diaphragms in the direction of the chord of the curvature of said diaphragms. v 3. In a sound reproducing device, an open sided rectangular box frame, a pair of straight-bordered curved diaphragms ithin said box frame arranged With their convex surfaces mutually oppositely and out Wardly directed and each secured by one straight border toone side of said box frame the opposite straight borders of said diaphragms being integrally united, and means mounted on said box 7 frame for vibrating said integrally united, borders in the direction of the chord of the curvature of said diaphragms. V

4. In a sound reproducing device, an o'pen sided rectangular box frame, a straight-bordered curved diaphragm of a size exceeding 2000 square centimetres Within said box frame and secured by one-straight border to oneside thereof, and means mounted on said box frame for vibrating the opposite straight border of said diaphragm in the direction of the chord of the curvature of said diaphragm.

5. In a sound reproducing device,-an open sided rectangular box frame, a pair of straight-bordered curved diaphragms each of a size exceeding 2000 square centimetres Within said box frame arranged With their convex -surfaces mutually oppositely and out- 'W'ardly directed and each secured by one stralght border to one side of said box frame,

and means mounted on said box frame for vibrating the opposite straight border of each of said diaphragms in the direction of the chord of the curvature of said .di'aphragms.

In testimony whereof, We aflix our signain tures. I

KARL LOCKE. HUGO SACHS. 

